Charging apparatus

ABSTRACT

A charging apparatus includes: a charging unit configured to perform a contactless charging operation for a placed external device; a detector configured to detect a position of a placed object; a determining unit configured to determine that the placed object is an external device compatible with the charging unit; and a control unit configured to control the charging unit such that, during the contactless charging operation for an external device compatible with the charging unit, the charging operation for the external device being charged is restricted when an object that is determined by the determining unit not to be an external device compatible with the charging unit, has been placed within a predetermined distance from the charging unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a charging apparatus, and in particularto a charging apparatus that provides electric power to external devicesusing electromagnetic induction.

2. Description of the Related Art

Contactless charging apparatuses that use electromagnetic induction havebeen known. Such charging apparatuses utilize the principle ofelectromagnetic induction in which a magnetic field generated by anelectric current flowing in a primary coil provided in a chargingapparatus causes a voltage to be generated across both ends of asecondary coil provided in an external device. In these chargingapparatuses, when a foreign object such as a piece of metal (forexample, a coin) is placed within the magnetic field generated by theprimary coil, an eddy-current flowing in the piece of metal may causeheat to be generated due to the internal resistance of the piece ofmetal.

To address such a problem, a charging apparatus has been proposed (forexample, US 2007/0069687) that does not activate a charging circuit ofthe charging apparatus until it detects that a chargeable device hasbeen placed on the charging apparatus, by means of authentication usinga contactless IC card.

However, the charging apparatus described above does not take intoconsideration a case in which a plurality of devices are being chargedin parallel. Hence, when a chargeable device and a non-chargeable deviceare placed on the charging apparatus at the same time, for example,there remains a problem in which a charging operation may possibly bestarted despite the presence of a non-chargeable device on the chargingapparatus, causing the non-chargeable device to generate heat.

SUMMARY OF THE INVENTION

The present invention addresses such problems as described above, andprovides a charging apparatus that can suppress heat generation evenwhen a non-chargeable device or a foreign object is placed together witha chargeable device on the charging apparatus.

According to an aspect of the present invention, a charging apparatusincludes a charging unit configured to perform a contactless chargingoperation for a placed external device; a position detector configuredto detect a position of a placed object; a determining unit configuredto determine whether the placed object is not an external devicecompatible with the charging unit; and a control unit configured tocontrol the charging unit such that, during the contactless chargingoperation for an external device compatible with the charging unit, thecharging operation for the external device being charged is restrictedwhen an object that is determined by the determining unit not to be anexternal device compatible with the charging unit, has been placedwithin a predetermined distance from the charging unit.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a structure of a charging apparatusaccording to a first embodiment of the present invention.

FIG. 2 is a block diagram of the charging apparatus according to thefirst embodiment of the present invention.

FIG. 3 is a flowchart showing the steps of a charging operation of thecharging apparatus according to the first embodiment of the presentinvention.

FIG. 4 is a perspective view of a structure of a charging apparatusaccording to a second embodiment of the present invention.

FIG. 5 is a block diagram of the charging apparatus according to thesecond embodiment of the present invention.

FIG. 6 is a flowchart showing the steps of a charging operation of thecharging apparatus according to the second embodiment of the presentinvention.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described in detail withreference to the attached drawings. A charging apparatus that can chargea plurality of devices will be described. Note that DC means directcurrent and AC means alternating current, hereinafter.

FIG. 1 shows a structure of a charging apparatus according to a firstembodiment. A charging apparatus 100 includes two coils 101 and 102. Amagnetic field generated by passing a current through each of the coils101 and 102 causes a voltage to be generated, due to electromagneticinduction, across both ends of a coil in a device to be charged that isplaced above the coil 101 or 102. The coils 101 and 102 may be exposedor may be covered with an outer case made of a non-conductive materialsuch as plastic or a resin.

The charging apparatus 100 also includes an IC communication unit 103used to communicate with an IC tag provided in a device being chargedthat is placed on the charging apparatus 100. An IC chip within the ICtag provided in the device being charged records therein informationindicating that the device being charged is a device that can be chargedwith the charging apparatus 100 of the present embodiment. The ICcommunication unit 103 receives the information indicating thechargeability of the device, and determines whether or not theinformation indicates that the device is chargeable with the chargingapparatus 100. The IC communication unit 103 may be either exposed orhoused in the outer case.

The charging apparatus 100 further includes a light emitting device(LED) 104 and a liquid crystal display (LCD) panel 105, used fornotifying a user of such occurrences as a charging error, a change instate of charging, and the completion of charging.

The charging apparatus 100 is also provided with a plurality oftemperature sensors such as thermistors 106 used for sensingtemperatures, and a plurality of magnetic sensors such as Hall elements107 used for sensing an object. The thermistors 106 and the Hallelements 107 may be either exposed or disposed under an outer casehaving a high thermal conductivity.

Referring to FIG. 1, a digital camera 110 is placed at a positioncorresponding to the coil 101 of the charging apparatus 100. The digitalcamera 110 includes a coil and an IC tag that records informationindicating that the camera 110 is a device chargeable with the chargingapparatus 100 according to the present embodiment. The digital camera110 can charge a secondary battery within the camera 110 using theprinciple of electromagnetic induction. Here, the digital camera 110 isassumed to include an IC tag and a coil, but an external unit includingan IC tag and a coil may be used to charge the digital camera 110.Further, even when a device has no secondary battery within it, thedevice can be made to operate normally by starting a charging operation.

Referring to FIG. 1, the outline of the charging operation is described.

Although a digital camera is described as a device to be charged, thedevice may be any electronic device, such as a cellular phone, aportable audio player, a portable game player, or a notebook personalcomputer.

When the Hall elements 107 sense that the digital camera 110 has beenplaced above the coil 101, the IC communication unit 103 communicateswith the IC tag in the digital camera 110. Specifically, a radio wavetransmitted from the IC communication unit 103 is received by theantenna of the IC tag in the digital camera 110, and the IC tag isactivated using electromotive force generated due to resonance effect ofthe antenna. Then information is read out from the IC chip in the IC tagand is transmitted from the antenna of the IC tag. The information readout from the IC chip in the IC tag of the digital camera 110 is receivedby the IC communication unit 103 of the charging apparatus 100. Theinformation received from the IC tag of the digital camera 110 is usedto determine whether or not the device is chargeable. When the receivedinformation indicates that the device is chargeable, the device isdetermined to be chargeable, and when the received information indicatesthat the device is not chargeable, the device is determined to benon-chargeable. When no information is received even though the ICcommunication unit 103 started communication (for example, when anobject with no IC tag is placed or when activation of an IC tag fails),the device is determined to be non-chargeable. The operation describedabove is called “IC authentication” hereafter in the present embodiment.

When the result of “IC authentication” shows that the informationreceived from an IC tag indicates a chargeable device, a current ispassed through the coil 101, which generates a magnetic field.

The coil built into the digital camera 110 charges the secondary batteryutilizing electromotive force due to the magnetic field generated in thecoil 101.

Alternatively, the generated electromotive force may be used to providepower to be consumed by the digital camera 110 during normal operation,instead of being used for charging the secondary battery.

The system configuration of the charging apparatus 100 according to thepresent embodiment will now be described.

FIG. 2 shows block diagrams of the charging apparatus 100 according tothe present embodiment and a charging circuit of the digital camera 110.

The charging apparatus 100 includes the coils 101 and 102, the ICcommunication unit 103, the LED 104, the LCD panel 105, the thermistors106, and the Hall elements 107. The charging apparatus 100 also includesa control unit 201 that controls each of its blocks. The chargingapparatus 100 also includes, as circuits for feeding the coils 101 and102, a commercial-power-supply input unit 202, a rectifier circuit 203,a DC/DC converter 204, charging controllers 205 and 206, and ACgenerators 207 and 208. The charging apparatus 100 also includes adisplay controller 209 that controls the display operation of the LED104 and the LCD panel 105. The charging apparatus 100 also includes atemperature detector 210 that sends temperature values sensed by thethermistors 106 to the control unit 201 and an object detector 211 thatdetects the strengths of magnetic fields at positions where the Hallelements 107 are located and sends information on the presence orabsence of an object to the control unit 201. The charging apparatus 100also includes a detecting unit 212 that detects voltages and/or currentsof the coils 101 and 102.

In the present embodiment, the input AC from a commercial power supplyis converted to a DC in the charging apparatus 100, but this conversionmay be performed by an AC adapter etc. connected to the chargingapparatus 100.

The digital camera 110, which is a device to be charged, has a block fora charging operation including a coil 221, a rectifier circuit 222, apower supply controller 223, a secondary battery 224, and an IC tag 225.

Referring to FIG. 2, a normal charging operation of the presentembodiment will now be described.

When the digital camera 110 is placed on the charging apparatus 100, theobject detector 211, receiving signals indicating changes in magneticfield sensed by the Hall elements 107, detects the position of an objectand notifies the control unit 201 of the placement and the position ofthe object. Then the IC communication unit 103 is controlled by thecontrol unit 201 to start “IC authentication”. The IC communication unit103 performs “IC authentication” of the IC tag of the digital camera110, and determines whether or not the placed object is a chargeabledevice.

When it is determined, as the result of the “IC authentication”, that achargeable device has been placed, the IC communication unit 103notifies the control unit 201 that a chargeable device has been placed.

As for a power supply, an AC voltage from the commercial-power-supplyinput unit 202 is rectified by the rectifier circuit 203 to produce a DCvoltage to be applied to the DC/DC converter 204. The DC/DC converter204 converts the input DC voltage to a predetermined voltage, which isapplied to the charging controllers 205 and 206.

The control unit 201, when notified by the IC communication unit 103that a chargeable device has been placed, controls the chargingcontrollers 205 and 206 that receive the DC voltage provided from theDC/DC converter 204, such that DC voltages are applied to the ACgenerators 207 and 208. Here, the control unit 201 controls the currentsand/or voltages supplied to the AC generators 207 and 208, bycontrolling the charging controllers 205 and 206. The AC generators 207and 208 convert the input DC voltages to AC voltages, which are appliedto the coils 101 and 102. The coils 101 and 102 generate AC magneticfields in accordance with the applied AC voltages. The digital camera110 includes a charging mechanism. The AC magnetic field generated bythe coil 101 causes an AC voltage to be generated across both ends ofthe coil 221 provided in the digital camera 110. The generated ACvoltage is rectified by the rectifier circuit 222 of the digital camera110, and the obtained DC voltage is applied to the power supplycontroller 223, which charges the secondary battery 224.

A normal charging operation is thus performed.

Referring to FIGS. 2 and 3, a method for controlling a chargingoperation according to the present embodiment will now be described.

FIG. 3 is a flowchart showing the steps of a charging operationaccording to the present embodiment.

The charging apparatus 100 performs “IC authentication” when it detectsthat an object has been placed (YES in step S301). When the object isdetermined to be a chargeable device as the result of the “ICauthentication” (YES in step S302), the control unit 201 causes ACmagnetic fields to be generated in the coils 101 and 102, by controllingthe charging controllers 205 and 206 (step S303). The AC magnetic fieldsgenerated in the coils 101 and 102 enable charging to be performedinside the placed chargeable device.

The detecting unit 212, during the charging, continues to send thecurrent and voltage data of the coils 101 and 102 to the control unit201. When the device being charged no longer needs to be charged since,for example, the charging has finished, the power consumed in the devicebeing charged drops, which leads to a drop in current of thecorresponding coil. In the present embodiment, for example, the powersupply controller 223 monitors the voltage of the secondary battery 224,and when it detects that the voltage has reached a predeterminedvoltage, suppresses the requirement for power. This leads to a drop incurrent of the corresponding coil 101. The control unit 201, whichdetected a drop in current of the coil 101 and/or the coil 102,determines that charging is no longer required. When a drop is notobserved, it is determined that charging is still required (step S304).

When it is determined that charging is no longer required (YES in stepS304), the control unit 201 controls the charging controllers 205 and206 such that supplying of power to the coils 101 and 102 is stopped,and instructs the display controller 209 to notify a user of completionof the charging operation. The display controller 209 makes the LED 104blink, be turned on, or change the luminescent color; or makes the LCDpanel 105 display a completion-of-charging message, for example (stepS305). The completion of charging may be notified by means of display asdescribed above, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

When the object is determined to be a non-chargeable device as theresult of the “IC authentication” (NO in step S302), the control unit201 determines whether or not the charging controllers 205 and 206 arein a state of supplying currents to the coils 101 and 102 (step S306).This is equivalent to determining whether or not AC magnetic fields havealready been generated in the coils 101 and 102, or determining whetheror not a certain chargeable device has already been placed in a state ofbeing charged. An alarm message may be displayed which shows that anon-chargeable device or a foreign object has been placed when theobject is determined to be a non-chargeable device as the result of the“IC authentication” (NO in step S302).

When currents are not being supplied to the coils 101 and 102 (NO instep S306), the control unit 201 instructs the display controller 209 todisplay an alarm showing that a non-chargeable device or a foreignobject has been placed (step S307). The display controller 209 makes theLED 104 blink, be turned on, or change the luminescent color to act asan alarm. Likewise, the LCD panel 105 displays a message acting as analarm. The alarm may be realized by display as described above, or maybe an audio message from a loudspeaker (not shown).

When currents are being supplied to the coils 101 and 102 (YES in stepS306), the control unit 201 receives the position data of the objectfrom the object detector 211. Then the control unit 201 determineswhether or not the newly placed object has been placed apart from thecoils 101 and 102 by a predetermined distance or more (step S308). Thisis equivalent to determining whether or not the newly placed object hasbeen placed within a predetermined distance from the coils 101 and 102.The object detector 211 can perform position detecting, i.e., locatingthe position of a placed object, by detecting and comparing all theoutputs of the Hall elements 107. Here, a predetermined distance means adistance beyond which a newly placed object, if made of metal, isunlikely to be heated due to magnetic fields generated by the coils 101and 102. It also means a distance within which a newly placed objectdisturbs electromagnetic induction utilized by a device that is alreadybeing charged. This may be determined on the basis of experiments, forexample.

When the distance between the newly placed object and the device beingcharged is a predetermined distance or more (YES in step S308), thecontrol unit 201 controls the charging controllers 205 and 206 such thatpower is continued to be supplied to the coils 101 and 102 (step S309).

When the device being charged no longer needs to be charged since thecharging has finished, for example, the power consumed in the devicebeing charged drops, which leads to a drop in current of thecorresponding coil. The control unit 201, which detected the drop incurrent of the coils 101 and 102, determines that charging is no longerrequired. When a drop is not observed, it is determined that charging isstill required (step S310).

When it is determined that charging is no longer required (YES in stepS310), the control unit 201 controls the charging controllers 205 and206 such that supplying of power to the coils 101 and 102 is stopped,and instructs the display controller 209 to notify a user of completionof the charging operation. The display controller 209 makes the LED 104blink, be turned on, or change the luminescent color; or makes the LCDpanel 105 display a completion-of-charging message, for example (stepS311). The completion of charging may be notified by means of display asdescribed above, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

When the distance between the newly placed object and the device beingcharged is less than a predetermined distance (NO in step S308), thecontrol unit 201 instructs the display controller 209 to display analarm showing that a non-chargeable device or a foreign object has beenplaced (step S312). The display controller 209 makes the LED 104 blink,be turned on, or change the luminescent color to act as an alarm.Likewise, the LCD panel 105 displays a message acting as an alarm. Thealarm may be realized by display as described above, or may be an audiomessage from a loudspeaker (not shown).

Then, the control unit 201 controls the charging controllers 205 and 206such that power is intermittently supplied to the coils 101 and 102. Bymeans of this control, the device being charged can be intermittentlycharged (step S313). The interval between the intermittent powersupplying operations is modifiable. At this time, the control unit 201may instruct the display controller 209 to notify a user of theintermittent charging by using the LED 104, the LCD panel 105, aloudspeaker (not shown), etc.

Next, the control unit 201 determines whether or not the temperatures ofthe device being charged and the newly placed object are abnormally highon the basis of temperatures detected by the temperature detector 210(step S314). The determination is made on the basis of the temperaturessensed by the thermistors 106 that are arranged near the position of thenewly placed object detected in step S306. A condition determined to beabnormal may be a temperature equal to or higher than a predeterminedvalue or a rate of increase in temperature equal to or higher than apredetermined value.

When the temperatures detected by the temperature detector 210 arenormal (YES in step S314), the control unit 201 determines whether ornot more charging is required on the basis of the voltage and currentdata of the coils 101 and 102 (step S315).

When it is determined that charging is no longer required (YES in stepS315), the control unit 201 controls the charging controllers 205 and206 such that supplying of power to the coils 101 and 102 is stopped,and instructs the display controller 209 to notify a user of completionof the charging operation. The display controller 209 makes the LED 104blink, be turned on, or change the luminescent color, or makes the LCDpanel 105 display a completion-of-charging message, for example (stepS311). The completion of charging may be notified by means of display asdescribed above, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

When it is determined that charging is still required (NO in step S315),the control unit 201 controls the charging controllers 205 and 206 suchthat the intermittent supply of power to the coils 101 and 102 iscontinued.

When the temperatures detected by the temperature detector 210 areabnormal (NO in step S314), the control unit 201 controls the chargingcontrollers 205 and 206 such that the voltage (charging voltage) appliedto the coils 101 and 102 becomes lower than before (step S316). At thistime, the control unit 201 may instruct the display controller 209 tonotify a user of lower-voltage charging by using the LED 104, the LCDpanel 105, a loudspeaker (not shown), etc.

Next, the control unit 201 determines whether or not the temperatures ofthe device being charged and the newly placed object are abnormally highon the basis of the temperatures detected by the temperature detector210 (step S317).

When the temperatures detected by the temperature detector 210 arenormal (YES in step S317), the control unit 201 determines whether ornot more charging is required on the basis of the voltage and currentdata of the coils 101 and 102 obtained by the detecting unit 212 (stepS318).

When it is determined that charging is no longer required (YES in stepS318), the control unit 201 controls the charging controllers 205 and206 such that supplying of power to the coils 101 and 102 is stopped,and instructs the display controller 209 to notify a user of completionof the charging operation. The display controller 209 makes the LED 104blink, be turned on, or change the luminescent color; or makes the LCDpanel 105 display a completion-of-charging message, for example (stepS311). The completion of charging may be notified by means of display asdescribed above, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

When the temperatures detected by the temperature detector 210 areabnormal (NO in step S317), the control unit 201 controls the chargingcontrollers 205 and 206 such that supplying of power to the coils 101and 102 is terminated (step S319), and instructs the display controller209 to notify a user that the charging operation has been terminated.The display controller 209 makes the LED 104 blink, be turned on, orchange the luminescent color; or makes the LCD panel 105 display atermination-of-charging message, for example (step S320). Thetermination of charging may be notified by means of display as describedabove, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

Note that the above-described sequence of steps S312 to S315 may beswapped with the above-described sequence of steps S316 to S318. Onlyone of the sequence of steps S312 to S315 and the sequence of steps S316to S318 may also be used.

By using the method of controlling a charging operation described above,a charging apparatus according to the present embodiment can suppressheat generation even when a non-chargeable device or a foreign object isplaced together with a chargeable device on the charging apparatus.Further, the possibility of unfavorably influencing the chargingoperation for a chargeable device can be lowered, and a chargeabledevice, if in a chargeable state, can be charged.

Another embodiment of a charging apparatus is described.

A charging apparatus using two coils was described in the firstembodiment. In a second embodiment, a charging apparatus using morecoils is described.

FIG. 4 shows a structure of a charging apparatus according to the secondembodiment. The components of the charging apparatus having functionssimilar to those of the components of the charging apparatus in thefirst embodiment are denoted by the same numerals and their descriptionsare omitted.

A charging apparatus 400 according to the present embodiment includescoils 401 to 406. These coils cause magnetic fields to be generated bypassing currents through them in a way similar to that in the coils ofthe first embodiment. A voltage is generated, due to electromagneticinduction, across both ends of a coil in a device to be charged that isplaced above the coils.

FIG. 5 is a block diagram of the charging apparatus 400 according to thepresent embodiment. The components having functions similar to those ofthe components in the first embodiment are denoted by the same numeralsand their descriptions are omitted.

Referring to FIG. 5, the charging apparatus 400 includes a control unit501 that controls each block of the charging apparatus 400. Chargingcontrollers 502 to 507 respectively control currents and/or voltagesprovided to AC generators 508 to 513. The AC generators 508 to 513convert the provided DC voltages to AC voltages, which are applied tothe coils 401 to 406.

The charging apparatus 400 according to the present embodiment canchange which coil power is supplied to in accordance with the positionof an object that is detected by the object detector 211. Specifically,the control unit 501 controls the charging controllers 502 to 507 suchthat power is supplied to a coil near the position of the objectdetected by the object detector 211. Here, the power may be supplied toa single or a plurality of coils. For instance, in the example shown inFIG. 4, since the position of the digital camera 110 can be detected, amagnetic field can be generated in the coil 404. The charging apparatus400 of the present embodiment can also charge one device using aplurality of coils.

Referring to FIGS. 5 and 6, a method for controlling a chargingoperation in the above-described charging apparatus 400 will now bedescribed.

FIG. 6 is a flowchart showing the steps of a charging operationaccording to the present embodiment.

The charging apparatus 400 performs “IC authentication” when it detectsthat an object has been placed (YES in step S601). When the object isdetermined to be a chargeable device as the result of the “ICauthentication” (YES in step S602), the control unit 501 causes an ACmagnetic field to be generated in a coil near the position where theobject has been placed, by controlling the charging controllers 502 to507 (step S603). The AC magnetic field generated in the coil enablescharging to be performed inside the placed chargeable device.

The detecting unit 212, during the charging, continues to send thecurrent and voltage data of the coil to the control unit 501. When thedevice being charged no longer needs to be charged since the charginghas finished, for example, the power consumed in the device beingcharged drops, which leads to a drop in current of the correspondingcoil. The control unit 501, which detected the drop in current of thecoil supplying power, determines that charging is no longer required.When a drop is not observed, it is determined that charging is stillrequired (step S604).

When it is determined that charging is no longer required (YES in stepS604), the control unit 501 controls the corresponding chargingcontroller such that supplying of power to the coil is stopped, andinstructs the display controller 209 to notify a user of completion ofthe charging operation. The display controller 209 makes the LED 104blink, be turned on, or change the luminescent color, or makes the LCDpanel 105 display a completion-of-charge message, for example (stepS605). The completion of charging may be notified by means of display asdescribed above, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

When the object is determined to be a non-chargeable device as theresult of the “IC authentication” (NO in step S602), the control unit501 determines whether or not any of the charging controllers 502 to 507is in a state of supplying a current to the corresponding coil (stepS606). This is equivalent to determining whether or not AC magneticfields have already been generated in some of the coils 401 to 406, ordetermining whether or not a certain chargeable device has already beenplaced in a state of being charged. An alarm message may be displayedwhich shows that a non-chargeable device or a foreign object has beenplaced, when the object is determined to be a non-chargeable device asthe result of the “IC authentication” (NO in step S602).

When currents are not being supplied to the coils 401 to 406 (NO in stepS606), the control unit 501 instructs the display controller 209 todisplay an alarm showing that a non-chargeable device or a foreignobject has been placed (step S607). The display controller 209 makes theLED 104 blink, be turned on, or change the luminescent color to act asan alarm. Likewise, the LCD panel 105 displays a message acting as analarm. The alarm may be realized by display as described above, or maybe an audio message from a loudspeaker (not shown).

Assuming that power is being supplied to the coils 402 and 405, forexample (YES in step S606), the control unit 501 determines whether ornot the newly placed object has been placed apart from the coils alreadyreceiving power by a predetermined distance or more (step S608). Theobject detector 211 can detect the position of the newly placed objectby detecting and comparing all the outputs of the Hall elements 107.Here, a predetermined distance means a distance beyond which a newlyplaced object, if made of metal, is unlikely to be heated, for example.This can be determined on the basis of experiments etc. Alternatively,the positional relationship may be checked as to whether or not thenewly placed object disturbs electromagnetic induction being utilized bya device that is already being charged. This can also be determined onthe basis of experiments etc.

When the distances between the newly placed object and the coils 402 and405 in a state of charging are a predetermined distance or more (YES instep S608), the control unit 501 controls the charging controllers 503and 506 such that power is continued to be supplied to the coils 402 and405 (step S609).

When the device being charged no longer needs to be charged since thecharging has finished, for example, the power consumed in the devicebeing charged drops, which leads to a drop in current of thecorresponding coils. The control unit 501, which detected the drops incurrent of the coils 402 and 405, determines that charging is no longerrequired. When a drop is not observed, it is determined that charging isstill required (step S610).

When it is determined that charging is no longer required (YES in stepS610), the control unit 501 controls the charging controllers 503 and506 such that supplying of power to the coils 402 and 405 is stopped,and instructs the display controller 209 to notify a user of completionof the charging operation. The display controller 209 makes the LED 104blink, be turned on, or change the luminescent color, or makes the LCDpanel 105 display a completion-of-charge message, for example (stepS611). The completion of charging may be notified by means of display asdescribed above, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

When the distances between the newly placed object and the coils 402 and405 in a state of charging are less than a predetermined distance (YESin step S608), the control unit 501 instructs the display controller 209to display an alarm showing that a non-chargeable device or a foreignobject has been placed (step S612). The display controller 209 makes theLED 104 blink, be turned on, or change the luminescent color to act asan alarm. The LCD panel 105 displays a message acting as an alarm. Thealarm may be realized by display as described above, or may be an audiomessage from a loudspeaker (not shown).

Assume that an object has been newly placed near the coil 402. Then thecharging controller 503 is controlled by the control unit 501 to stopsupplying power to the coil 402, which is within the predetermineddistance from the newly placed object (step S613). In this case, byproviding an LED etc. (not shown) near each coil, a user may be notifiedof the coil that has stopped receiving power using the illuminationstates of the LED. Alternatively, the LED 104 or the LCD panel 105 maybe used to notify the user of which coil has stopped receiving power.

Next, the control unit 501 determines whether or not the temperatures ofthe device being charged and the newly placed object are abnormally highon the basis of temperatures detected by the temperature detector 210(step S614). The determination is made on the basis of temperaturessensed by the thermistors 106 that are arranged near the position of thenewly placed object detected in step S606. The condition determined tobe abnormal may be a temperature equal to or higher than a predeterminedvalue or a rate of increase in temperature equal to or higher than apredetermined value.

When the temperatures detected by the temperature detector 210 arenormal (YES in step S614), the control unit 501 determines whether ornot more charging is required on the basis of the voltage and currentdata of the coil 405 (step S615).

When it is determined that charging is no longer required (YES in stepS615), the flow proceeds to step S611, where supplying of power to thecoil 405 is stopped and completion of the charging operation isnotified.

When the temperatures detected by the temperature detector 210 areabnormal (NO in step S614), the control unit 501 controls the chargingcontroller 506 such that power is supplied intermittently to the coil405 (step S616). At this time, the control unit 501 may instruct thedisplay controller 209 to notify a user of intermittent charging byusing the LED 104, the LCD panel 105, a loudspeaker (not shown), etc.

Next, the control unit 501 determines whether or not the temperatures ofthe device being charged and the newly placed object are abnormally highon the basis of the temperatures detected by the temperature detector210 (step S617).

When the temperatures detected by the temperature detector 210 arenormal (YES in step S617), the control unit 501 determines whether ornot more charging is required on the basis of the voltage and currentdata of the coil 405 (step S618).

When it is determined that charging is no longer required (YES in stepS618), the flow proceeds to step S611, where supplying of power to thecoil 405 is stopped and completion of the charging operation isnotified.

When the temperatures detected by the temperature detector 210 areabnormal (NO in step S617), the control unit 501 controls the chargingcontroller 506 such that the voltage applied to the coil 405 becomeslower than before (step S619). At this time, the control unit 501 mayinstruct the display controller 209 to notify a user of lower-voltagecharging by using the LED 104, the LCD panel 105, a loudspeaker (notshown), etc.

Next, the control unit 501 determines whether or not the temperatures ofthe device being charged and the newly placed object are abnormally highon the basis of the temperatures detected by the temperature detector210 (step S620).

When the temperatures detected by the temperature detector 210 arenormal (YES in step S620), the control unit 501 determines whether ornot more charging is required on the basis of the voltage and currentdata of the coil 405 (step S621).

When it is determined that charging is no longer required (YES in stepS621), the flow proceeds to step S611, where supplying of power to thecoil 405 is stopped and completion of the charging operation isnotified.

When the temperatures detected by the temperature detector 210 areabnormal (NO in step S620), the control unit 501 controls the chargingcontroller 506 such that supplying of power to the coil 405 isterminated (step S622), and instructs the display controller 209 tonotify a user that the charging operation has been terminated. Thedisplay controller 209 makes the LED 104 blink, be turned on, or changethe luminescent color, or makes the LCD panel 105 display atermination-of-charging message, for example (step S623). Thetermination of charging may be notified by means of display as describedabove, or may be notified by means of an audio message using aloudspeaker (not shown) etc.

Note that the sequence of steps S612 to S615, the sequence of steps S616to S618, and the sequence of steps S619 to S621 described above may beswapped with one another. Only one or two of these sequences of stepsmay also be used.

A charging apparatus according to the present embodiment can suppressheat generation even when a non-chargeable device or a foreign object isplaced together with a chargeable device on the charging apparatus.Further, the possibility of unfavorably influencing the chargingoperation for a chargeable device can be lowered, and a chargeabledevice, if in a chargeable state, can be charged.

In the first and second embodiments, a device to be charged is placed ona charging apparatus; however, by making the chargeable apparatus standon its side, a device to be charged may be placed near the coils, whichare now arranged along the vertical surface of the charging apparatus.For instance a device to be charged may be placed on stands that areprovided near the coils, or may be hanged using hangers such as hooksthat are provided such that the device is placed near the coils. Theseways of placement are also included in embodiments of the invention.

The method of contactless charging is not limited to the method ofcharging using electromagnetic induction as described in theembodiments. Other examples include a method of charging in which aradio wave transmitted from a charging apparatus is received with anantenna, and power is taken out from the received radio wave. Anotherexample is a method of charging in which a charging apparatus produces avibrating electric or magnetic field, which causes resonance in aresonant circuit provided in a device to be charged, allowing the deviceto take out power.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2008-057309 filed Mar. 7, 2008, which is hereby incorporated byreference herein in its entirety.

1. A charging apparatus comprising: a charging unit configured toperform a contactless charging process, wherein the contactless chargingprocess includes a process for supplying power to an external device;and a control unit configured to perform a predetermined process forreducing a voltage supplied to the external device based on whether adistance between an object and the charging apparatus is less than apredetermined value if the contactless charging process is performed,wherein the object does not include a chargeable device.
 2. The chargingapparatus according to claim 1, wherein the control unit controls thecharging unit to supply power to the external device intermittentlybased on whether the distance is less than the predetermined value ifthe contactless charging process is performed.
 3. The charging apparatusaccording to claim 1, wherein the object does not include a unit thatcharges by using power received from the charging apparatus.
 4. Thecharging apparatus according to claim 1, wherein the control unitcontrols the charging unit to stop the contactless charging processbased on whether the distance is less than the predetermined value ifthe contactless charging process is performed.
 5. The charging apparatusaccording to claim 1, further comprising an output unit that outputsinformation relating to the object if the distance is less than thepredetermined value.
 6. The charging apparatus according to claim 1,wherein the control unit stops the contactless charging process by usingat least one of a current of the charging unit and a voltage of thecharging unit if the contactless charging process is performed.
 7. Thecharging apparatus according to claim 1, wherein the control unitperforms the predetermined process if the contactless charging processis performed and the distance is less than the predetermined value. 8.The charging apparatus according to claim 1, further comprising adetector that detects a position of the object.
 9. A charging apparatuscomprising: a first charging unit configured to perform a contactlesscharging process, wherein the contactless charging process includes aprocess for supplying power to an external device; a second chargingunit configured to perform the contactless charging process; and acontrol unit configured to reduce a voltage supplied to the externaldevice based on whether a first distance between an object and the firstcharging unit is less than a predetermined value if the contactlesscharging process is performed by using the first charging unit, whereinthe object does not include a chargeable device.
 10. The chargingapparatus according to claim 9, wherein the control unit stops supplyingpower to the external device via the first charging unit based onwhether the first distance is less than the predetermined value if thecontactless charging process is performed by using the first chargingunit.
 11. The charging apparatus according to claim 9, wherein thecontrol unit controls the first charging unit to supply power to theexternal device intermittently based on whether the first distance isless than the predetermined value if the contactless charging process isperformed by using the first charging unit.
 12. The charging apparatusaccording to claim 9, wherein the object does not include a unit thatcharges by using power received from the charging apparatus.
 13. Thecharging apparatus according to claim 9, further comprising an outputunit that outputs information relating to the object if the firstdistance is less than the predetermined value.
 14. The chargingapparatus according to claim 9, wherein the control unit performs thecontactless charging process by using the second charging unit if thefirst distance is less than the predetermined value and a seconddistance between the object and the second charging unit is not lessthan the predetermined value.
 15. The charging apparatus according toclaim 9, wherein the control unit stops the contactless charging processby using at least one of a current of the first charging unit and avoltage of the first charging unit if the contactless charging processis performed by using the first charging unit.
 16. The chargingapparatus according to claim 9, wherein the control unit performs thepredetermined process if the contactless charging process is performedby the first charging unit and the first distance is less than thepredetermined value.
 17. The charging apparatus according to claim 9,further comprising a detector that detects a position of the object.